The objective of this study was to review the published research works on biological control of fungal plant diseases during past 50 years. Fungal plant pathogens are among the most important factors that cause serious losses to agricultural products every year. Biological control of plant diseases including fungal pathogens has been considered a viable alternative method to chemical control. In plant pathology, the term biocontrol applies to the use of microbial antagonists to suppress diseases. Throughout their lifecycle, plants and pathogens interact with a wide variety of organisms. These interactions can significantly affect plant health in various ways. Different mode of actions of biocontrol-active microorganisms in controlling fungal plant diseases include hyperparasitism, predation, antibiosis, cross protection, competition for site and nutrient and induced resistance. Successful application of biological control strategies requires more knowledge-intensive management. Various methods for application of biocontrol agents include: application directly to the infection court at a high population level to swamp the pathogen, application at one place in which biocontrol microorganisms are applied at one place (each crop year) but at lower populations which then multiply and spread to other plant parts and give protection against pathogens and one time or occasional application that maintain pathogen populations below threshold levels. Commercial use and application of biological disease control have been slow mainly due to their variable performances under different environmental conditions in the field. To overcome this problem and in order to take the biocontrol technology to the field and improve the commercialization of biocontrol, it is important to develop new formulations of biocontrol microorganisms with higher degree of stability and survival. Majority of biocontrol products are applied against seed borne and soil borne fungal pathogens, including the causal agents of seed rot, damping-off and root rot diseases. These products are mostly used as seed treatment and have been effective in protecting several major crops such as wheat, rice, corn, sugar beet and cotton against fungal pathogens. However, in some cases, biocontrol microorganisms have also been tested as spray application on foliar diseases, including powdery mildew, downy mildew, blights and leaf spots. A few post harvest fungal diseases have also been controlled by the use of antagonistic fungi and bacteria. Biocontrol microorganisms are also being used as the form of composts in some plants. Research data and observations in nurseries have shown that addition of composted organic matter to potting mixes results in suppression of soil borne diseases. A significant improvement have been made in different aspects of biological control of fungal plant diseases, but this area still need much more development and investigations to solve the existing problems. In order to have more effective biological control strategies in the future, it is critical to carry out more research studies on some less developed aspects of biocontrol, including development of novel formulations, understanding the impact of environmental factors on biocontrol agents, mass production of biocontrol microorganisms and the use of biotechnology and nano-technology in improvement of biocontrol mechanisms and strategies. Future outlooks of biocontrol of plant diseases is bright and promising and with the growing demand for biocontrol products among the growers, it is possible to use the biological control as an effective strategy to manage plant diseases, increase yield, protect the environment and biological resources and approach a sustainable agricultural system.
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"The most practical method for application of biocontrol agents in the field is developing and preparing powdery formulations which will enable the farmers to use them as seed treatment particularly for controlling seed and root diseases. Studies have shown that the efficacy of some microbial antagonists in biological control of different plant diseases has been preserved and increased after they have been mixed with organic and inorganic carriers (Heydari and Pessarakli 2010; Kakvan et al. 2013; Samavat et al.2014 ). Garlic is an important crop grown in many countries around the world including Iran (Clarkson et al., 2002; Mahdizadehnaraghi et al., 2007; Bakonyi et al., 2011). "
[Show abstract][Hide abstract] ABSTRACT: ABSTRACT: Twelve bioformulations were developed using six isolates of three antagonistic fungi (two isolates each) and two organic and inorganic carriers. Spore suspension of fungal isolates including Trichoderma harzianum, T. asperellum and Talaromyces flavus were prepared and were mixed with two powdery carriers including rice bran and talc following standard procedure. Prepared bioformulations were then used as garlic seed (bulb) treatment to promote three growth factors of garlic including plant height, bulb fresh weight and bulb dry weight in a green house experiment. The design of the experiment was completely randomized with 13 treatments (12 bioformulations and an untreated control) each with four replications. Results showed that all bioformulations had enhancing effects on the growth characteristics in comparison with the untreated control. According to the results, rice bran-based bioformulations performed more effectively than those of talc-based and placed in different statistical groups. Among the fungal isolates, T. harzianum, T. asperellum and Talaromyces flavus showed the most effectiveness in the enhancement of garlic height, bulb fresh weight and bulb dry weight respectively. The overall results of this study suggest that development and application of bioformulations containing antagonistic fungi may be an effective and environmentally safe method for the promotion of garlic growth.
"These microbial antagonists are known as biological control agents (BCAs). The interaction of a BCA and a pathogen include: (i) mycoparasitism, the pathogen is directly attacked by a BCA that kills it or its propagules; (ii) antibiosis and metabolite production, i.e., the BCAs produce substances that are toxic to the pathogen; (iii) competition for nutrients, i.e., the BCAs occupy the same ecological niche of the pathogen and therefore deplete the nutrients necessary for its establishment ; (iv) induction of the plant defence system, i.e., the stimulation of the host plant defences by the presence of the BCAs; and (v) the barrier effect, caused by the presence of mycorrhizal fungi (Schoeman et al. 1999; Alabouvette et al. 2006; Ownley and Windham 2007; Heydari and Pessarakli 2010; Diez and Alves- Santos 2011). Among the potential BCAs there are several fungal endophytes, i.e., fungi that live inside the plant tissue and maintain either a neutral, detrimental or beneficial relationship with the host plant (Sieber 2007; Backman and Sikora 2008). "
[Show abstract][Hide abstract] ABSTRACT: Biological control agents (BCAs), and among them some species of fungal endophytes, are potential substitutes for chemical pesticides in the control of plant diseases due to their non-toxicity to human beings and their surrounding environment. One mode of action of fungal BCAs is through their bioactive, extracellular products, which can inhibit the growth of pathogens. In this study, the effect of fungal filtrates from four endophyte isolates (Trichoderma viride, Aureobasidium pullulans, Aureobasidium sp. and the unknown endophyte 20.1) on the advance of the pathogen Gremmeniella abietina on 2-year Pinus halepensis seedlings was evaluated. Both preventive and therapeutic treatments of the filtrates were studied by applying the filtrates either before or after the pathogen inoculation, respectively. Since G. abietina is a necrotrophic fungus, the length of the necrosis produced by the pathogen was used as response variable in our experiment. In order to explore the chemical composition of the fungal filtrates, a simple HPLC screening of UV-absorbing components was conducted. The results of the study showed that all fungal filtrates were able to reduce the advance of G. abietina when compared to the control seedlings, regardless of the time of inoculation and the treatment. Low-molecular weight phenolic compounds could be detected in some but not all filtrates, warranting further studies on the possible role of these compounds in fungal filtrates.
European Journal of Plant Pathology 08/2015; DOI:10.1007/s10658-015-0719-3 · 1.49 Impact Factor
"The use of chemical fungicides as seed treatment is the most common strategy for controlling this disease in the field. Most of the time, this strategy is not effective due to the long application time, and the appearance of resistant races of the pathogen (Heydari and Passarakli 2010). In addition, the high production cost of the chemical fungicides and the negative impacts on nontarget organisms must be considered. "
[Show abstract][Hide abstract] ABSTRACT: White rot disease caused by Sclerotium cepivorum is a major yield reducing fungal disease of garlic found throughout the world, including Iran. The use of chemical fungicides is the most common control method for the disease at the present time. This control measure is costly, contaminates the environment, and harms non-target organisms. Moreover, since the pathogen is soil-borne, chemical control strategy is not quite effective against the disease. In this study, we tried to develop and prepare some new bioformulations based on three antagonistic fungal species: Trichoderma harzianum, T. asperellum, and Talaromyces flavus. Six isolates of the above-mentioned fungi were used along with the organic and inorganic carriers, rice bran and talc, to develop twelve new bioformulations. The effectiveness of the bioformulations were then evaluated in the control of garlic white rot disease in the greenhouse conditions in comparison with the healthy control, infected control, and the commonly used fungicide Carbendazim. The design of the experiment was completely randomised. There were 15 treatments each, with four replicates. The results of the greenhouse experiments indicated that almost all the developed bioformulations resulted in significant reductions (34.50 to 64.50%) in the incidence of white rot disease. In general, bioformulations which contained the organic carrier (rice bran) performed more effectively than those that contained the inorganic carrier (talc). Bioformulations which contained an organic carrier (rice bran) were as effective as the fungicide Carbendazim.